Molecular characterization of atmospheric NO2-responsive germin-like proteins in azalea leaves.
Atmospheric nitrogen dioxide (NO(2)) is an environmental oxidant that is removed through direct uptake by foliage, but plant responses to this highly reactive gas are not well understood at the molecular level. From NO(2)-exposed leaves of a woody azalea (Rhododendron mucronatum), we cloned two cDNAs (RmGLP1 and RmGLP2) for germin-like proteins (GLPs), a group of ubiquitous plant proteins that have been implicated in various plant physiological and developmental processes. Quantitative analysis of mRNA expression, together with immunoblotting data, showed that foliar exposure to NO(2) caused a robust induction of these GLP-encoding genes. When produced in tobacco cell culture, recombinant RmGLP2 was secreted into the apoplast, where it exhibited superoxide dismutase activity. RmGLP1 and RmGLP2 represent the first examples of plant genes that are responsive to airborne NO(2). These enzymes might have a potential role in extracellular defense mechanisms through attenuation of interactions between reactive nitrogen and oxygen species.
Kondo
Komei
K
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
Yamada
Keizo
K
Nakagawa
Ayami
A
Takahashi
Misa
M
Morikawa
Hiromichi
H
Sakamoto
Atsushi
A
D000595:Amino Acid Sequence; D001272:Atmosphere; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009585:Nitrogen Dioxide / Q000378:metabolism* / Q000494:pharmacology; D010083:Oxidants, Photochemical / Q000378:metabolism* / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D029793:Rhododendron / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics
D018076:DNA, Complementary; D006023:Glycoproteins; D010083:Oxidants, Photochemical; D010940:Plant Proteins; D009585:Nitrogen Dioxide